Coupling nut



FIG. 1 is a top plan view of a coupling nut in accordance with my design;

FIG. 2 is a top, front, left perspective view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a bottom, right, rear perspective view thereof;

FIG. 5 is a front elevational view thereof, with the rear elevational view being identical thereto; and,

FIG. 6 is a right side elevational view thereof, with the left side elevational view being identical thereto. 

CLAIM The ornamental design for a coupling nut, as shown and described. 